Fabric process

ABSTRACT

A process for imparting stretch characteristics to a woven fabric comprising applying greater than usual warp yarn tension to a fabric in a plurality of increments and then setting the fabric in its new configuration.

D United States Patent [151 3,655,327 Rollins [451 Apr. 11, 1972 [54] FABRIC PROCESS References Cited [72] Inventor: William H. Rollins, Spartanburg, S.C. UNITED STATES PATENTS [73] Assignee: Deering Millikan Research Corporation, 2,173,997 9/ 1939 Burgeni ..28/ l Spartanburg 3,120,095 2/ 1964 Guthrie 3,190,718 6/1965 Schoeneberg ..8/130.1 [22] Filed: Sept. 19, 1969 FOREIGN PATENTS OR APPLICATIONS [21] App]. No.: 871,397

983,968 2/ 1965 Great Britain Related U.S. Application Data Primary Examiner-George F. Lesmes [63] Continuation-impart of Ser. No. 458,955, May 26, Assistant E i |3, g m

1965, abandoned. Attorney-Norman C. Armitage and H. William Petry 52 U.S. Cl. ..s/130.1, 8/DIG. 3, 57/157 ABSTRACT [51] Int. Cl. ..D06m A02g 3/04 A process f imparting Stretch characteristics to a woven [58] Field Of Search ..8/130.1; 57/555, 157 fabric comprising applying greater than usual warp yam tension to a fabric in a plurality of increments and then setting the fabric in its new configuration.

13 Claims, 9 Drawing Figures 5 U R F A C E PREPARATION TENSIONED DESIZING 8| SCOURING RELAX TENSIONED MERCERIZING OR OPEN WIDTH WASHING RELAX FINISH PATENTEDAPR I I I972 3, 655.327

sum 1 [IF 2 SURFACE PREPARATION TENSIONED DESI ZING 8| SCOURING RELAX TENSIONED MERCERIZING OR OPEN WIDTH WASHING RELAX TENSIONED HEAT SETTING WITH OPTIONAL DYEING FINISH Fl 6 -l- INVENTOR.

WILLIAM H.ROLLINS ATTORNEY PATEMTEQAPR 1 1 I972 SHEET 2 UF 2 nah 3%;

FIG. 4- FIG.

FIG. '6- F/G' -7...

INVENTOR WILLIAM H. ROLLINS ATTORNEY FABRIC PROCESS This application is a continuation-impart of application Ser. No. 458,955, filed May 26, 1965, now abandoned.

This invention relates to the preparation of stretch fabric and more specifically to the preparation of stretch fabric hav ing elastic characterisfics in the direction of the fill yarns.

In general, elastic effects are produced in a fabric either by preparing fabrics from elastic yarns or by compacting preformed fabrics prepared from yarns having no prior stretch characteristics. Stretch yarns are commonly prepared by employing an elastomeric component as a core about which nonelastic fibers are spun. A second means for producing stretch yarn is by compacting or crimping the yarns or the filament fibers employed in the preparation of the yarns. Methods which are commonly employed for preparation of such noncore spun stretch yarns are gear crimping, knit-unknit methods, edge-crimping, belt crimping, blowing methods and twist-set-untwist methods.

While stretch fabrics may be prepared from the stretch yarns produced according to any of the aforementioned processes, great care must be exercised in the preparation of the stretch fabrics to insure that the elastic characteristics of the yarns are not lost in the subsequent knitting or weaving operations.

It is therefore often desirable to produce stretch characteristics in preformed fabrics. Stretch fabrics produced in the piece are now being prepared according to U.S. Pat. Nos. 3,077,655; 2,765,513; and 2,765,514. The first of these patented processes involves a combination of factors among which are fabric construction, chemical treatments and mechanical action. In its most general terms, the process set forth in U.S. Pat. No. 3,077,655 involves the preparation of a loosely constructed fabric from high twist wool yarns, immersion of the fabric in reducing agent followed by agitation of the fabric between vibrating members whereby the fabric is alternately compacted and released thereby permitting the high twist yarns to contract and create a stretch fabric having elastic characteristics in both the warp and fill direction. Another process for the preparation of stretch fabric is embodied in U.S. Pat. Nos. 2,765,513 and 2,765,514. The process set forth in these two patents involves the compacting of a fabric in the direction of the warp yarns by the passage of the fabric into a machine consisting of two rolls and a blade. The blade is in close proximity to the upper roll to form a primary feed nip. A fabric entering the apparatus between the blade and a smooth compounded upper roll assumes the speed of that roll. The fabric then passes from this primary nip to a second nip formed by the two rolls themselves. The lower roll possessing a higher coefficient of friction than the top roll and traveling at a slower speed than the top roll takes control of the fabric from the top roll because the fabric is being fed into the apparatus at a faster rate by the first nip and is being taken away at a slower rate. At the second nip the column of fabric supported between the nip is under a state of lateral compression and a fabric having elastic characteristics in the direction of the warp yarns is created.

Processes are also known for the preparation in the piece of stretch fabrics having stretch characteristics in the direction of the fill yarns, such fabrics being produced by a process which is commonly known as crimp inter-change. The method of producing a stretch fabric by means of crimp inter-change is set forth in British Pat. No. 983,968, published Feb. 24, 1965. The crimp inter-change process imparts stretch characteristics to a woven fabric by means of applying a load in the direction of the warp yarns while maintaining the fill yarns in an unrestrained configuration thereby allowing the fill yams to relax suitably by at least to 30 percent thereby bringing about yarn crimp inter-change between the yarns in the two directions of the woven fabric. The fabric is preferably prepared from yarns containing at least some thermoplastic fibers whereby a heating operation may be carried out upon the fabric which has previously undergone the crimp interchange process and thereby secure the fabric in its new configuration. Such a process while producing a desirable product does not lend itself to existing fabric finishing operations, that is to say the process must be conducted as a separate operation with separate equipment thereby increasing the time and expense of producing a finished product.

It is therefore an object of this invention to provide a process for producing a fabric by means of a crimp interchange process which may be integrated with existing fabric finishing operations.

It is another object of this invention to provide a process for the preparation of a stretch fabric by means of a crimp interchange process which develops stretch characteristics in successive increments.

These and other objects will become more apparent from the following description of the invention.

In accordance with this invention it has now been discovered that it is possible to produce a fabric having stretch characteristics along the direction of the fill yarns by means of a precess comprising applying greater than usual warp yarn tension to a fabric in a plurality of increments which may be successive increments and preferably in three increments. It is preferred that the fabric be allowed to relax after each application of warp yarn tensions and still more preferably, that each following increment of warp yarn tension be of greater magnitude than the preceding increment of warp yarn tension. In general, the warp yarn tensions applied to the fabric to effect crimp inter-change are less than about 200 pounds per inch. The term relax as employed herein is deemed to mean a substantial lessening of warp yarn tensions on the fabric, that is to say reducing warp yarn tensions at least to a point below those tensions which are calculated to produce crimp interchange. As a final step in the process of this invention, the fabric after having been subjected to a plurality of increments of warp yarn tensions is set in its new configuration.

The warp yarn tensions applied to the fabric to effect crimp inter-change should be sufiicient to accomplish a substantial reduction in the width of the fabric and greater than usual warp tension. Depending upon the type of fabric, ordinarily about one pound or so tension per inch of fabric width is applied to fabric during processing. Thus, the warp yarn tension should be greater than about one pound per inch of fabric width. For example, in the processing of a 60 inch wide fabric, the total tension should exceed about sixty pounds. The maximum tension is not critical but again dependent upon the type of fabric being processed. The tension should be below that which will destroy or degrade the yarns in the fabric and preferably is less than about percent of the breaking strength of the fabric. Thus, the warp yarn tension during the tensioning steps of the process of the invention will be between about one pound and 200 pounds per inch of fabric width and more particularly between about 2 pounds and pounds, with a preferred range of about 3 pounds to 25 pounds per inch. LIkewise, the maximum tension advantageously is less than about 60 percent of the breaking strength of the fabric being processed.

The lessening of the warp yarn tension during the relaxing step as pointed out above should be less than tensions which produce crimp inter-change and less than normal processing tensions, i.e., less than one pound or so per inch of fabric width. Advantageously, the warp yarn tension during fabric relaxation should approach zero. The duration of the tensioning and relaxing operations may vary considerably. Generally, the tensioning steps are performed on a running fabric so that the tension is maintained for a relative short time. Advantageously, the tension is maintained for less than about 2 minutes and preferably between about 15 seconds and 60 seconds. The relaxation generally is of considerably longer duration. For example, if the yarn is relaxed in a scray, the relaxation period may be fi-om several minutes to a number of hours, e.g., 2 minutes to 24 hours and preferably 5 minutes to 4 hours.

Specific fabric setting treatments which are suitable for purposes of this invention are the use of a reducing agent setting operation for yarns containing keratinous fibers, the use of cross linking agents in the setting of cellulosic type yarn and the use of heat setting means for thermoplastic yarns, the selection of the particular setting medium being employed, depending, of course, on the type of fiber present to the greatest degree in the yarn or the percentage of fibers of a particular nature coupled with the ability of such fibers to obtain a permanent set. The preferred fabric for purposes of this invention is a thermoplastic fiber containing fabric and still more preferably a polyester fiber containing fabric. Fiber blends which are preferred are polyester fiber-cellulosic fiber blends and polyester fiber-wool fiber blends. The heat setting operation carried out on thermoplastic fiber containing fabrics is therefore especially suited to this invention.

The construction of the fabrics suitable for undergoing a crimp inter-change process is, of course, a construction which will admit to a compacting along the direction of the filling yarns. Preferably, the construction is a square construction, that is to say a construction having an equal number of picks and ends per inch. The preferred fabric should also have a cover factor of about 13, the proper cover factor being produced by the preparation of a fabric having a construction such that:

ends or picks per inch A better understanding of the invention may be had from a discussion of the drawings in which:

FIG. 1 is a flow sheet of one means for carrying out the crimp inter-change process of this invention.

FIG. 2 is a microphotograph of a fabric prior to undergoing the crimp inter-change of this invention.

FIG. 3 is a microphotograph of a fabric subsequent to undergoing the crimp inter-change process of this invention.

FIG. 4 is a microphotograph of a warp yarn of the fabric of FIG. 2.

FIG. 5 is a microphotograph of a fill yarn of the fabric of FIG. 2.

FIG. 6 is a microphotograph of a warp yarn of the fabric of FIG. 3.

FIG. 7 is a microphotograph of a fill yarn of the fabric of FIG. 3.

FIG. 8 is a microphotograph of a cross section of the fabric of FIG. 2 taken along the direction of the fill yarns.

FIG. 9 is a microphotograph of a cross section of the fabric of FIG. 3 taken along the direction of the fill yarns.

Turning to FIG. 1 of the drawings, a flow sheet is set forth for a generalized procedure for preparing the stretch fabrics of this invention. As may be seen from the drawings, a surface preparation such as a singeing operation is carried out on the fabric so as to burn off the fuzz or hairiness of the cloth and obtain a smooth surface. Before singeing, the cloth is preferably brushed and sheared to remove lint, dust, loose yarns, loops, etc. The singed fabric is then desized and scoured under warp yarn tensions of less than about 200 pounds per inch by passage into a range which is preferably of the twostage type. The goods after being wetted out are passed through a squeeze roll into a saturator containing caustic soda solution and then into an enclosed J box. A U-shaped arrangement is attached to the front part of the J box for rapid and uniform saturation of the cloth with steam before it is passed down into the J box. Stretch characteristics in the fill yarn direction of from about 5 to about 10 percent are imparted at this point. The fabric is allowed to relax to substantially lesser warp yarn tensions and is then passed into a mercerizing unit Where it is treated under tensions of less than about 200 pounds per inch with a strong solution of sodium hydroxide at room temperature. If so desired, an open width wash rather than a mercerizing operation may be carried out at this point. The second tensioning operation is found to impart additional stretch characteristics in the fill yarn direction of from about 10 percent to about percent. The fabric is again allowed to relax to substantially lesser warp yarn tensions and is then passed under warp yarn tensions of less than about 200 pounds per inch into a liquor which lubricates the fabric and facilitates crimp inter-change. The fabric is then dried at temperatures of from about 375 F to about 400 F the temperature varying, of course, depending upon the specific fiber components of the fabric. The final tensioning operation is found to impart additional stretch characteristics in the fill yarn direction of from about 5 percent to about 10 percent. Should a colored fabric be desired, the liquor may be a dye bath liquor. The fabric now set in its new configuration and having stretch characteristics of from about 20 percent to about 35 percent along the direction of the fill yarns is given the usual fabric finish such as passage into a calender where a series of rolls are arranged so that a polished metallic roll alternates with a cotton wrapped roll thereby producing a leveling and lustering effect upon the fabric. The calendered fabric is then passed into a finishing bath which in the case of cellulosic fiber containing fabrics is commonly a starch solution or a carboxymethyl cellulose solution or combinations of any of the foregoing.

One example among the wide range of processing conditions suitable in the above process of the invention would involve desizing of the starch sized fabric with a dilute aqueous enzyme solution (e.g., 1 percent) at a temperature of about l60-l F. for about one hour. The scouring step would employ a dilute caustic soda solution of about 0.5 to 3.5 percent concentration for another hour. The mercerizing solution utilized in the second tensioning step contains about 20-25% sodium hydroxide. The temperature of the mercerizing solution may be about room temperature or above (70-l 10 F.), and the treating period may be about 30-60 seconds. If the final tensioning operation is accomplished by dyeing in a Thermosol range, the temperature, for example, may be between about 400-425 F. for 60-90 seconds with a polyester/cotton fabric.

While fabrics having stretch characteristics of up to about 35 percent in the direction of the fill yarns and more specifically from about 20 percent to about 35 percent in the direction of the fill yarns may be produced by the mechanical process previously set forth, it is possible to exceed the 35 percent figure by incorporating certain chemical reagents in the lubricating or dye liquor. The chemical reagent should have the ability to swell at least some of the fiber components of the warp yarns and thereby render the warp yarns amenable to further stretching and the fabric to further crimp inter-change. A swelling agent which has been found to be suitable for polyester fibers is hot (about C.) dimethyl sulfoxide.

The following specific examples of process for the preparation of a stretch fabric of this invention are given for purposes of illustration and should not be considered as limiting the spirit or scope of this invention.

EXAMPLE I A 50% polyester/50% polynosic cellulosic fabric prepared from single twenties yarn in both warp and fill directions and having a woven construction of 58 X 50 in the gray is passed through the processing operations set forth in the description of FIG. 1. The fabric is found to have a width of 64 k inches at the loom. After the first tensioning operation, the fabric is found to have a construction of 64 X 48 and to be 58 inches wide. After heat setting, the fabric is found to have a construction of 81 X 47 and to be 47 inches wide with the finished construction being 76 X 46 with a width of approximately 48% inches. The fabric is found to have a stretch in the fill yarn direction of 27.5 percent with 4.8 percent being nonrecoverable stretch.

EXAMPLE II A 65% polyester/35% cotton fabric prepared from single twenty sixes yarn in both warp and fill direction and having a construction of 96 X 54 was processed according to the procedure set forth in the discussion of FIG. 1. The fabric is EXAMPLE III A 65% polyester/35% cotton fabric is prepared from a single fifties yarn in both warp and fill direction and having a construction of 88 X 72 and being 65.7 inches wide in the loom. The fabric is processed according to the procedure set forth in the description of FIG. 1 of the drawings. After the first tensioning operation, the fabric is found to have a construction of 104 X 53 and to be 59 inches wide. After heat setting, the fabric has a construction of 112 X 52 and is 55 inches wide. The finished product is 112 X 51 in construction and is 55 inches in width having a stretch of 21 percent in the fill yarn direction.

EXAMPLE IV A 55% polyester/45% wool worsted fabric is prepared from single twenties yarn in both warp and fill direction havinga construction of 42 X 45 and being 86 9% inches wide in the loom. The fabric is processed according to the procedure set forth in the description of FIG. 1 of the drawings. After the first tensioning operation the fabric is found to have a construction of 48 X 44 and to be 76 inches wide. After being relaxed and then undergoing open width washing followed by relaxation and final tension heat setting operations, the fabric is found to be 72 inches wide and to have a construction of 52 X 42 and to have about 17 percent stretch in the fill yarn direction.

The determination of elasticity in the finished product as reported in the foregoing examples was determined by cutting test specimens 2 inches by 24 inches with the longer length being parallel to the stretch direction. The upper end of the test specimen is then secured to a clamp member while the lower end of the test specimen is subjected to a load of 4 pounds (2 pounds per inch). The specimen is then exercised by cycling three times between a zero load and a 2 pound load at approximately 5 seconds per cycle. The increase in length is then recorded within 30 seconds after completion of the fourth loading cycle. The increase in length over the initial length multiplied by 100 is then recorded as a percent stretch.

The extent to which a crimp inter-change has taken place is readily discemable from a review of FIGS. 2-9 which are enlarged photographs of the fabrics, fabric cross sections and yarns as set forth in Example III, prior to crimp inter-change and subsequent to crimp inter-change. While crimp interchange may be observed to a certain extent by comparison of FIGS. 2 and 3 of the drawings, FIG. 2 being a microphotograph of fabric prior to having undergone crimp interchange while FIG. 3 is a microphotograph of a fabric subsequent to having undergone crimp inter-change, the differences in the geometry of fabric construction are more readily apparent by comparison of the warp yarns before undergoing crimp interchange as illustrated in FIG. 4 of the drawings and warp yarn subsequent to having undergone crimp inter-change as illustrated in FIG. 5 of the drawings. The distinctions in geometry of construction are also readily apparent by comparison of the fill yarns as illustrated in FIG. 6 of the drawings before having gone through the crimp inter-change process and the fill yarns as illustrated in FIG. 7 of the drawings, after having undergone crimp inter-change. A comparison of FIGS. 8 and 9 of the drawings will also serve to show the increase in the frequencies and amplitude of the undulations of the fill yarns produced by a straightening of the warp yarns, FIG. 8 being a cross section of a fabric taken along the direction of the fill yarns prior to having undergone a crimp inter-change process and FIG. 9 being a cross section of the same fabric taken along the direction 0 the fill yarns after having undergone a crimp inter-change process.

When crimp inter-change takes place, the slightly undulating parallel warp yarns of the fabric are pulled substantially straight, and at the same time, the parallel fill yarns in the other direction are thereby pulled further apart and the undulating path over and under the substantially straight warp yarns in the other direction is very much enhanced. It is therefore readily appreciated that any assistance which can be afforded the movement between the yarns will improve the process. Apparently, tensioning the warp yarns in a plurality of increments and especially increments which are spaced by periods of warp yarns relaxation allow the individual fibers to adjust themselves to their new configuration and to be more amenable to accepting still further crimp inter-change.

That which is claimed is:

l. A process for imparting stretch characteristics to a woven fabric which comprises applying a first warp yarn tension to a fabric in an amount greater than usual warp yarn tension and between about 1 and 200 pounds per inch, reducing the warp yarn tension to substantially zero to relax said fabric, applying a second warp yarn tension to said relaxed fabric in an amount greater than usual warp yarn tension and between about 1 and 200 pounds per inch, reducing the warp yarn tension to substantially zero to relax said fabric, and applying a third warp yarn tension to said fabric in an amount greater than usual warp yarn tension and between about 1 and 200 pounds per inch, and heating said fabric to set its new configuration.

2. The process of claim 1 wherein said starting fabric has a cover factor of about 13 and contains at least 50 percent thermoplastic fibers.

3. The process of claim 1 wherein the fabric contains at least 50 percent polyester fibers.

4. The process of claim 1 wherein the warp yarn tension in each of the tensioning steps is between about 2 and pounds per inch.

5. The process of claim 1 wherein the warp yarn tension in each of the tensioning steps is between about 3 and 25 pounds per inch.

6. The process of claim 1 wherein each successive increment of warp yarn tension is of increased magnitude.

7. The process of claim 1 wherein the fabric is heated to at least about 375 F. to set its new configuration.

8. The process of claim 1 wherein the fabric is heated to a temperature between about 375 and 425 F. to set its new configuration.

9. The process of claim 1 wherein said fabric is a wool fiberpolyester fiber blend.

10. The process of claim 1 wherein said fabric is a cellulosic fiber-polyester fiber blend fabric.

I l. The process of claim 1 wherein said thermoplastic fibers are subjected to the action of a swelling agent while warp yarn tension is applied to said fabric.

12. The process of claim 1 wherein said fabric is a square weave fabric.

13. The process of claim 1 wherein said fabric is subjected to the action of a lubricating agent and a swelling agent while warp yarn tension is applied to said fabric. 

2. The process of claim 1 wherein said starting fabric has a cover factor of about 13 and contains at least 50 percent thermoplastic fibers.
 3. The process of claim 1 wherein the fabric contains at least 50 percent polyester fibers.
 4. The process of claim 1 wherein the warp yarn tension in each of the tensioning steps is between about 2 and 150 pounds per inch.
 5. The process of claim 1 wherein the warp yarn tension in each of the tensioning steps is between about 3 and 25 pounds per inch.
 6. The process of claim 1 wherein each successive increment of warp yarn tension is of increased magnitude.
 7. The process of claim 1 wherein the fabric is heated to at least about 375* F. to set its new configuration.
 8. The process of claim 1 wherein the fabric is heated to a temperature between about 375* and 425* F. to set its new configuration.
 9. The process of claim 1 wherein said fabric is a wool fiber-polyester fiber blend.
 10. The process of claim 1 wherein said fabric is a cellulosic fiber-polyester fiber blend fabric.
 11. The process of claim 1 wherein said thermoplastic fibers are subjected to the action of a swelling agent while warp yarn tension is applied to said fabric.
 12. The process of claim 1 wherein said fabric is a square weave fabric.
 13. The process of claim 1 wherein said fabric is subjected to the action of a lubricating agent and a swelling agent while warp yarn tension is applied to said fabric. 